Data entry of all the addresses that the OCRs failed to read.

OCR was pretty bad back in 1995 (which is why the Palm Pilot had a special handwriting for users to learn).

See this NPR piece: http://www.npr.org/2010/12/28/132393643/Undeliverable-Mail-I...

Also "Act Three" of Episode 70 of "This American Life": https://www.thisamericanlife.org/radio-archives/episode/70/o...